This invention relates generally to the antenna arts and more particularly to a novel and improved horn-type antenna.
Generally speaking, a horn antenna may be defined as an expanded opening of desired size formed in a cross section of a wave guide. More particularly, a horn antenna comprises a rectilinear flared horn-like structure coupled to a cross sectional opening in a rectangular wave guide, at least one side thereof diverging or flared out to define an enlarged rectangular opening. The area about which the expanded or diverging horn meets the wave guide is generally referred to as a throat.
The two dimensions or surfaces of a rectangular wave guide are generally referred to as H and E surfaces with reference to the lines of magnetic (H) and electric (E) force associated with wave guide theory. A horn antenna may be formed by the expansion or divergence of either or both of these H and E surfaces of a rectangular wave guide. In this regard, a so-called "fan shaped horn antenna" is one in which the expansion or divergence is of only one of these H and E surfaces.
While the invention may find other utility, the ensuing description will be facilitated with specific reference to horn antennas for transmitting and receiving in the X and K bands of electromagnetic radiation. In this regard, the X band comprises waves in the frequency range of between 10.500 GHz and 10.550 GHz, while the K band comprises electromagnetic waves in the frequency range between 24.050 GHz and 24.250 GHz.
In accordance with the invention, a surprising improvement is realized in the receiving sensitivity of such a horn antenna. Moreover, the sensitivity differences known to exist between the horizontal and vertical polarization of the electromagnetic radiation can be substantially eliminated by the invention. Accordingly, improved reception for X and K band signals can be obtained at any angular position at which the antenna may be mounted with respect to an incoming signal, without experiencing such polarization differences.